Charged particle device and wiring method

ABSTRACT

An object of the present invention is to provide: a wiring method in which wiring is performed in a vacuum chamber of a charged particle device without using gas deposition or the like; and a charged particle device. 
     In order to achieve the above-described object, the present invention proposes: a wiring method in which a wiring line composed of an ionic liquid is formed by dropping an ionic liquid on a sample or preparing an ionic liquid on a sample table, on which a sample is placed in advance, and irradiating a wiring track between a wiring start point and a wiring end point with a charged particle beam; and a charged particle device. According to this configuration, wiring can be performed in a vacuum chamber of a charged particle device without using a gas deposition method or the like.

TECHNICAL FIELD

The present invention relates to a charged particle device and a wiringmethod, more particularly relates to a wiring method using an ionicliquid, and a charged particle device including an ionic liquid source.

BACKGROUND ART

It has been demanded that a microregion on the nanoscale or microscalebe observed using an electron microscope. As an observation method or ameasurement method therefor, there are an observation method in whichobservation is made while applying a voltage to a microregion of asample, a measurement method in which an absorbed electron current of amicroregion is measured using an electron microscope, an observationmethod in which observation is made using an electron microscope in astate where a microregion is grounded, and the like.

In the case where observation or measurement as described above is made,local wiring is sometimes performed in a microregion so that localvoltage application or local ground connection can be made.

As a method of performing local wiring, there is a gas deposition methodusing a focused ion beam as disclosed in PTL 4.

Further, PTL1 discloses a method of forming a conductive pattern byinkjet printing using an ink containing conductive particles and anionic liquid. The ionic liquid has a characteristic that a liquid stateis maintained even under vacuum conditions.

PTL 2 discloses a method of observing a biological sample in itsoriginal form by impregnating or applying an ionic liquid into or onto awater-containing sample so as to prevent the evaporation of water undervacuum conditions.

Further, PTL 3 discloses an observation method in which an ionic liquidis held in a sample holding member having an opening, and a sample isfloated in the ionic liquid and observed.

CITATION LIST Patent Literature

PTL 1: JP-A-2006-335995

PTL 2:WO2007/083756 (corresponding to U.S. Pat. No. 7,880,144)

PTL 3: JP-A-2009-266741 (corresponding to US Published PatentApplication No. 2011/0057100)

PTL 4: JP-A-2002-110680

SUMMARY OF INVENTION Technical Problem

In the case of a gas deposition method using an ion beam as disclosed inPTL 4, once wiring is performed, in order to remove the wiring line, itis necessary to scrape off the processed region by irradiating theregion with an ion beam again for removing it, and therefore, there is aconcern about damage at this time. Further, in the case of a method offorming a wiring line using inkjet printing as disclosed in PTL 1, it isnecessary to perform wiring using a dedicated printing device, andtherefore, wiring cannot be performed while making observation using anelectron microscope or the like. Further, PTL 2 and PTL 3 do notdisclose or suggest that wiring is performed in a local region of asample.

Hereinafter, a wiring method for the purpose of performing wiring in avacuum chamber of a charged particle device without using gas depositionor the like, and a charged particle device will be described.

Solution to Problem

As one embodiment for achieving the above-described object, hereinafter,a wiring method in which a wiring line composed of an ionic liquid isformed by dropping an ionic liquid on a sample or preparing an ionicliquid on a sample table, on which a sample is placed in advance, andirradiating a wiring track between a wiring start point and a wiring endpoint with a charged particle beam, and a charged particle device willbe described.

Advantageous Effects of Invention

According to the above-described embodiment, it becomes possible toperform wiring in a vacuum chamber of a charged particle device withoutusing a gas deposition method or the like.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structural view of a charged particle device.

FIG. 2 is a view showing one example of an ionic liquid introductionmechanism.

FIG. 3 is an enlarged view of a probe section of the ionic liquidintroduction mechanism.

FIG. 4 is a view illustrating a phenomenon that an ionic liquid is movedby electron beam irradiation.

FIG. 5 is a view illustrating a phenomenon that the ionic liquid movesaccompanying the movement of the irradiation position of an electronbeam.

FIG. 6 is a flowchart showing the steps of a wiring method.

FIG. 7 is a view showing an outline of the steps of the wiring method.

FIG. 8 is a flowchart 1 showing the steps of an automatic wiring method.

FIG. 9 is a flowchart 2 showing the steps of the automatic wiringmethod.

FIG. 10 is a view showing a movement track of an electron beamirradiation region (horizontal direction).

FIG. 11 is a view showing a movement track of an electron beamirradiation region (vertical direction).

FIG. 12 is a view showing a movement track of an electron beamirradiation region (oblique direction).

FIG. 13 is a view showing one example of a sample exchange chamber.

FIG. 14 is a view showing one example of a GUI screen for setting wiringconditions.

FIG. 15 is a view showing one example of a sample rotating rod tip and asample table bottom.

FIG. 16 is a view showing an external appearance of a liquid bath forthe ionic liquid.

FIG. 17 is a view showing one example of a sample table on which theionic liquid can be placed.

FIG. 18 is a view showing an ionic liquid supply method.

FIG. 19 is a view showing one example of a setting device which setswiring conditions and a control device of an electron microscope.

FIG. 20 is a view showing one example of an SEM image when settingwiring conditions.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a method in which in a charged particle device, a mechanismcapable of introducing an ionic liquid into a sample chamber isdisposed, an ionic liquid is dropped on a sample at an arbitraryposition, and the dropped ionic liquid and/or a wiring track between awiring start point and a wiring endpoint are/is irradiated with acharged particle beam to guide the ionic liquid to an arbitraryposition, thereby moving the ionic liquid to another position, wherebyarbitrary two positions are electrically wired, and the device will bedescribed.

According to a method and a device described hereinbelow, a method and adevice capable of forming and removing a wiring line in a microregionwhile suppressing damage to a sample can be realized.

First Embodiment

Hereinafter, a wiring method using an ionic liquid and a device will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view showing a structure of a charged particledevice. Reference numeral 101 denotes a vacuum chamber, which can bemaintained in a vacuum state by a vacuum pumping system 102. Referencenumeral 103 denotes a sample exchange mechanism, which can introduce asample to be observed into the device from the outside while maintainingthe vacuum chamber 101 in a vacuum state. Reference numeral 104 denotesa charged particle beam source, which includes a cathode and an anodefor generating a charged particle beam, and all the necessary opticalsystems such as a lens and an aperture for focusing the generatedcharged particle beam, and a scanning coil for scanning the chargedparticle beam. By the above-described optical systems in the chargedparticle beam source 104, a charged particle beam 105 can be focused ona sample 106, and scanned in an arbitrary order.

A secondary signal 107 generated on the surface of the sample 106 by theirradiation with the charged particle beam 105 is detected by asecondary signal detection system 108, and is input as image data to acontrol system 109 which also has an image arithmetic control function.The sample 106 is fixed on a sample table 110 with a conductive tape,paste, or the like, and can be moved in every three-dimensionaldirection by a sample stage 111.

The control system 109 also controls the charged particle beam source104, the secondary signal detection system 108, the sample stage 111, anionic liquid introduction mechanism 113, and an image display device112. A signal detected by the secondary signal detection system. 108 isamplified by a signal amplifier in the control system 109, andthereafter transferred to an image memory, and displayed and recorded asa sample image in the image display device 112. Reference numeral 113denotes the ionic liquid introduction mechanism, which can drop an ionicliquid on the sample 106 at an arbitrary position.

One example of the ionic liquid introduction mechanism 113 is shown in aschematic view in FIG. 2. Reference numeral 201 denotes a liquid tank,which can store an ionic liquid 202 to be dropped on the sample.Reference numeral 203 denotes an inlet, through which the ionic liquid202 can be poured into the liquid tank 201. Further, to the inlet 203, acap which can keep the inside of the liquid tank 201 airtight isattached. Reference numeral 204 denotes a vacuum pumping system, whichcan perform vacuum pumping in the liquid tank 201. Reference numeral 205denotes a shutter, which separates the inside of the charged particledevice from the liquid tank 201, and is closed when the pressure in theliquid tank 201 is atmospheric pressure so that the vacuum chamber 101can be kept vacuum, and is opened when the inside of the liquid tank 201is in a vacuum state so that the ionic liquid 202 can be allowed to flowout from the liquid tank 201. At this time, by adjusting the openingdegree, the flow rate of the ionic liquid can be adjusted. Referencenumeral 206 denotes a probe rod, which has a hollow space therein, andthe inside of the hollow space is in a vacuum state or the ionic liquidflowing out from the liquid tank 201 can be allowed to flowtherethrough. To the tip of the probe rod 206, a probe 209 is attachedthrough a rough movement mechanism 207 using a mechanical structure anda fine movement mechanism 208 using a piezoelectric element, so that theprobe 209 can be accurately moved closer to or away from the sample. Therough movement mechanism 207 and the fine movement mechanism 208 eachhave a hollow space therein in the same manner as the probe rod 206, andthe ionic liquid flowing out from the liquid tank 201 and flowingthrough the probe rod 206 can be allowed to flow to the probe 209. Thevacuum pumping system 204, the shutter 205, the rough movement mechanism207, and the fine movement mechanism 208 are controlled by the controlsystem 109 shown in FIG. 1. Further, a mechanism which generates apotential difference between the tip of the probe 209 and the sampletable connected to the ground, and measures a current therebetween isprovided, and the control of the mechanism is carried out using thecontrol system 109.

FIG. 3 shows an enlarged view of the probe 209. The probe 209 is fixedto a probe fixing section 301, and can be freely removed and replaced.In the probe fixing section 301, a hole 302 is formed, and the ionicliquid flowing out from the liquid tank 201 and flowing through theprobe rod 206, the rough movement mechanism 207, and the fine movementmechanism 208 can be allowed to flow along the surface of the probe 209.The ionic liquid 303 flowing along the surface of the probe 209 can bedropped on the surface of the sample 106 from the tip of the probe 209.A very shallow groove may be formed from the hole 302 to the tip of theprobe 209 so as to make the ionic liquid flow smoothly to the tip.Further, in order to improve the wettability with respect to the ionicliquid, the roughness of the surface of the probe 209 may be adjusted.

According to the above-described configuration, by the charged particledevice of this embodiment, the probe is moved closer to a sample to beobserved and the ionic liquid can be dropped thereon while observing thesurface of the sample. Further, after dropping the ionic liquid, theprobe can also be moved away from the sample so as not to disturb theobservation.

Second Embodiment

FIG. 4 shows secondary electron images of an ionic liquid droplet on aSi substrate observed using a scanning electron microscope: FIG. 4(a)shows a secondary electron image before irradiating the droplet with anelectron beam; and FIG. 4(b) shows a secondary electron image afterirradiating the droplet with an electron beam. In FIG. 4(a), a blackregion denoted by reference numeral 401 is an ionic liquid droplet, andthe other region denoted by reference numeral 402 is a Si substrate. Itwas observed that when a region 403 to be irradiated with an electronbeam is irradiated with an electron beam, the ionic liquid spreads overa region 404 irradiated with the electron beam as shown in FIG. 4(b).Further, FIG. 5 shows a secondary electron image observed after theionic liquid droplet was irradiated with an electron beam whilegradually moving the irradiation region away from the liquid droplet. Inthe same manner as in FIG. 4, a black region denoted by referencenumeral 501 is an ionic liquid droplet, and the other region denoted byreference numeral 502 is a Si substrate. As a result of irradiating theregion irradiated with an electron beam 503 with an electron beam whilegradually moving the region in the direction of the arrow, it wasobserved that the ionic liquid moves as if it is attracted to the regionirradiated with the electron beam. Based on the above results, it wasfound that the ionic liquid can be guided by electron beam irradiation.

This phenomenon is considered to be caused by the effect of a potentialchange due to the electron beam irradiation or by convection of theionic liquid receiving the energy of the electron beam, and may becaused not only by an electron beam, but also by any charged particlebeam. It is also considered that a potential change or convection ismore likely to occur as the energy of electron beam or the amount ofcurrent is larger, and the guide speed is increased. However, when anexcessively high energy or high amount of current is applied, the ionicliquid itself may be deteriorated to impair the fluidity. The energy ofelectron beam is preferably from about 1 to 30 kV, and the amount ofcurrent is preferably from about 1 to 50 pA.

Further, in the case where a sample is charged by beam irradiation, andthe ionic liquid is attracted to the sample due to the charging, itbecomes possible to guide the ionic liquid in a desired direction byirradiating not the ionic liquid itself but a track for guiding theionic liquid (in the case where wiring is performed, a wiring trackbetween a wiring start point and a wiring end point), which ispositioned apart from the ionic liquid, with a beam as long as the trackis within a range in which the electric field due to charging isexerted. However, if the beam irradiation position and the ionic liquidare separated too far, the electric field for guiding the ionic liquidmay not be exerted on the ionic liquid. Therefore, for example, in thecase where automatic processing is performed, it is preferred to set theprocessing conditions so that the distance between the beam irradiationposition and the ionic liquid is not more than a predetermined value atwhich the influence of the electric field is considered to be exerted.On the other hand, if the beam irradiation regions are separated fromeach other, a disconnection may occur, and therefore, in light of thepurpose of ensuring wiring connection, as illustrated in FIGS. 10 to 12,it is preferred to provide an overlapping portion between adjacentfields of view. Further, it is also possible to move the irradiationposition while continuously performing beam irradiation.

FIG. 6 is a flowchart showing the steps of a wiring method. FIG. 7 is aschematic view illustrating the steps of the wiring method. A sample tobe observed is inserted in a charged particle device, and observation isstarted (Step 601). Subsequently, a stage is moved to adjust a field ofview to a target position A701 on the sample (Step 602). Subsequently,by using the rough movement mechanism and the fine movement mechanismdescribed in the first embodiment, the probe 209 is moved closer to thesample 106 (Step 603). By using the probe 209, an ionic liquid 702 isdropped on the target position A701 (Step 604). The probe 209 is movedaway from the sample 106 (Step 605). The magnification is increasedaccording to a desired linewidth (Step 606). The field of view isadjusted so as to include an edge portion of the ionic liquid droplet704, and a charged particle beam is irradiated (Step 607). When theionic liquid spreads over a region irradiated with the charged particlebeam, the field of view is moved to the next field of view. At thistime, an overlapping portion is provided such that about 20 to 50% ofthe field of view overlaps with the previous field of view (Step 608).By repeating Step 607 and Step 608, the ionic liquid is guided (Step609). When the ionic liquid reached a target position B703, the chargedparticle beam irradiation is terminated (Step 610). By theabove-described steps, the target positions A and B are electricallywired to each other through the ionic liquid.

In this device, the above-described operation can be performed whilemaking observation and wiring can be performed in a microregion on thenanoscale to microscale. Further, by using an electron beam as thecharged particle beam 105, damage to a sample which is a matter ofconcern when adopting a method using gas deposition with a focused ionbeam can be reduced.

Third Embodiment

The charged particle device described in this embodiment canautomatically guide the ionic liquid by charged particle beamirradiation in the wiring method shown in the second embodiment. Here,an automatic wiring method will be described in two ways depending onhow the timing of the movement of the field of view is controlled.

FIG. 8 is a flowchart showing the steps when the timing of the movementof the field of view is controlled according to time. First, theirradiation time per irradiation region is set (Step 801). Subsequently,the magnification for the irradiation region is determined according toa desired linewidth, and the number of fields of view is set accordingto the distance between the target positions A and B (Step 802).Automatic wiring is started (Step 803). By using the irradiation regionA as a start point, the charged particle beam irradiation isautomatically started at the set magnification (Step 804). The chargedparticle beam irradiation is automatically terminated according to theset irradiation time (Step 805). The stage is automatically moved to theirradiation region B, and the charged particle beam irradiation isautomatically started again (Step 806). The charged particle beamirradiation is automatically terminated according to the set irradiationtime (Step 807). The stage movement (to an irradiation region C, anirradiation region D and the charged particle beam irradiation arerepeated automatically (Step 808). The set number of fields of view isreached (Step 809). By the above-described steps, the ionic liquid canbe automatically guided by the charged particle beam irradiation bycontrolling the timing of the movement of the field of view according totime.

FIG. 9 is a flowchart showing the steps when the timing of the movementof the field of view is controlled according to a contrast change due tothe spreading of the ionic liquid over the whole field of view. In thesecondary electron images shown in FIGS. 4 and 5, the ionic liquidportion is observed with darker contrast as compared with the Sisubstrate, however, the contrast changes according to the type of theionic liquid or the Si substrate. Therefore, first, the contrast ratioof the ionic liquid and the Si substrate is measured in each case (Step901). Based on the contrast ratio measured in Step 901, setting is madeas to what percentage of the field of view over which the ionic liquidspreads is reached when the field of view is to be moved (Step 902). Themagnification for the irradiation region is determined according to adesired linewidth, and the number of fields of view is set according tothe distance between the target positions A and B (Step 903). Automaticwiring is started (Step 904). By using the irradiation region A as astart point, the charged particle beam irradiation is automaticallystarted at the set magnification (Step 905). The contrast change due tothe spreading of the ionic liquid is detected, and the charged particlebeam irradiation is automatically terminated according to the setpercentage (Step 906). The stage is automatically moved to theirradiation region B, and the charged particle beam irradiation isautomatically started again (Step 907). The contrast change due to thespreading of the ionic liquid is detected, and the charged particle beamirradiation is automatically terminated according to the set percentage(Step 908). The stage movement (to an irradiation region C, anirradiation region D . . . ) and the charged particle beam irradiationare repeated automatically (Step 909). The set number of fields of viewis reached (Step 910). By the above-described steps, the ionic liquidcan be automatically guided by the charged particle beam irradiation bycontrolling the timing of the movement of the field of view according toa contrast change due to the spreading of the ionic liquid over thewhole field of view.

FIGS. 10 to 12 are schematic views showing the movement of theirradiation region in automatic wiring. FIG. 10 shows the case where theirradiation region is moved in the horizontal direction; FIG. 11 showsthe case where the irradiation region is moved in the verticaldirection; and FIG. 12 shows the case where the irradiation region ismoved in the oblique direction. Reference numerals 1001, 1101, and 1201each denote an irradiation region A, reference numerals 1002, 1102, and1202 each denote an irradiation region B, and Reference numerals 1003,1103, and 1203 each denote an irradiation region C. According to thenumber of fields of view set in Steps 802 and 903, an irradiation regionD, an irradiation region E, and so on follow. As described above, anoverlapping portion is provided between adjacent regions such as theirradiation regions A and B, and the irradiation regions B and C suchthat about 20 to 50% of the irradiation regions overlap with each other.In the flowcharts shown in FIGS. 8 and 9, the case where the irradiationregion is moved in the direction from A to Cis described, however, theirradiation region may be moved in the reverse direction. Further, thehorizontal direction, the vertical direction, and the oblique directionmay be combined, and wiring can be performed flexibly according to thesituation. The magnification may be changed for each of the irradiationregions, and also the linewidth of the wiring line can be changedaccording to the situation.

By automating the above-described movement of the irradiation regionunder software control, wiring can be automatically performed. It isalso possible to automate the movement in the horizontal direction andthe vertical direction by using a continuous image capturing functionprovided for an SEM.

Fourth Embodiment

In this embodiment, the ionic liquid used for wiring can also be removedas needed. FIG. 13 is a schematic view showing the structure of thesample exchange mechanism 103 shown in FIG. 1. Reference numeral 1301denotes a sample, which is fixed to a sample table 1302. The sampletable 1302 having the sample 1301 fixed thereto is attached to the tipof a sample exchange rod 1303. By moving the sample exchange rod 1303left or right, the sample can be moved in and out between a samplecamber and a sample exchange chamber. Reference numeral 1304 denotes asample exchange chamber, in which vacuum pumping is performed as apreliminary step for inserting the sample in the sample chamber. The tipof the sample exchange rod 1303 has a structure employing a banana clipsystem or a two-rod structure.

On the sample table 1302, a receiving section for receiving the sampleexchange rod is provided. Further, the sample exchange rod 1303 can alsorotate about its axis. Reference numeral 1305 denotes a sample rotatingrod, which can move up and down. Further, it can be rotated about itsaxis by a sample rotating rod control section 1306.

FIG. 15 shows a schematic view showing the attachment of a samplerotating rod tip 1501 to a sample table bottom 1502. The sample rotatingrod tip 1501 has a cylindrical shape and has a hollow space therein, andis processed to have a screw groove 1503 therein. In the sample tablebottom (rear surface) 1502, a screw groove 1504 (receiving side) isprovided, and the sample rotating rod tip can be attached to the sampletable bottom.

At this time, the direction of tightening the screw and the direction ofactually rotating the sample are the same, and therefore, even when theaxis of the sample rotating rod 1305 rotates, the sample table bottom1502 and the sample rotating rod tip 1501 are not detached from eachother. When the sample table bottom 1502 and the sample rotating rod tip1501 are detached from each other, by rotating the sample rotating rod1305 in the loosening direction in a state where the sample exchange rod1303 is attached, the sample rotating rod 1305 can be detached withoutrotating the sample table. It is a matter of course that the sampletable does not fall down.

Reference numeral 1307 denotes a liquid bath, which plays a role incollecting the removed ionic liquid. Reference numeral 1308 denotes anattachment, which serves as a structure for attaching/detaching theliquid bath 1307 to/from the bottom of the sample exchange chamber. Asshown in FIG. 16, a liquid bath bottom 1601 and the sample exchangechamber bottom 1602 are attached and fixed to each other by theattachments 1308. Reference numeral 1309 denotes a gate valve, whichseparates the sample exchange chamber from the sample chamber, and isopened and closed only when the sample table is moved in and out betweenthe sample camber and the sample exchange chamber.

The sample exchange rod is rotated at 180 degrees (inverted), and thesample table is turned upside down. Subsequently, the sample rotatingrod is attached to the screw groove on the bottom of the sample table,and the sample exchange rod is detached (withdrawn). By utilizing thevertically moving mechanism of the sample rotating rod, the sample tableis lowered so that the surface of the sample is in the liquid bath. Byutilizing the rotating mechanism of the sample rotating rod, the ionicliquid is thrown away by the centrifugal force. The rotating mechanismmay be operated by either manual drive or automatic drive using a motoror the like.

The ionic liquid scattered at this time is adhered to the side walls ofthe liquid bath and collected in the liquid bath. By utilizing thevertically moving mechanism of the sample rotating rod, the sample tableis raised, the sample exchange rod is attached, and the sample rotatingrod is detached. The sample exchange rod is rotated about its axis, andthe sample is turned upside down. The valve disposed between the samplechamber and the sample exchange chamber is opened, and the sample tableis inserted in the sample chamber, and only the sample exchange rod isdrawn out. Then, the valve disposed between the sample chamber and thesample exchange chamber is closed, and the charged particle beamirradiation is performed in the charged particle device, and observationis made.

As a method of removing a local wiring line, a focused ion beam is used,however, a focused ion beam is used also for making observation, andtherefore, there is a concern about damage to the sample duringobservation. In addition, the sample may be damaged also when a wiringline is scraped off by a focused ion beam. In the charged particledevice of this embodiment, by using an electron beam as the chargedparticle beam, damage to the sample, which is a matter of concern whenusing a focused ion beam can be reduced, and a local wiring line can beremoved.

Fifth Embodiment

In this embodiment, one example of the sample table on which the ionicliquid and the sample are placed will be described. A schematic view ofthe sample table is shown in FIG. 17. It does not matter whether thesample table 1701 is made of aluminum or carbon and has a stub shape, oris made of another conductive material and has another shape. The sampletable 1701 is grounded through the sample stage 111 shown in FIG. 1. Asample 1702 fixed to the sample table 1701 is brought to such a statethat it is not in electrically contact with the sample table such as apattern on a glass substrate. When such a sample is irradiated with thecharged particle beam, electric charges are accumulated on the surfaceof the sample, and in the case of electron microscopic observation, aneffect such as image drift or abnormal contrast appears. A case wherecharging is suppressed by grounding such a sample will be described. Onthe surface of the sample table 1701, a hole 1703, which has a diameterof about 1 to 5 mm and a depth of about 1 to 5 mm, is present, and anionic liquid 1704 is held therein in advance. The ionic liquid 1704 heldtherein is irradiated with a charged particle beam 1705, and guided andmoved to a target position of the sample. According to theabove-described configuration, the sample 1702 is grounded through theionic liquid 1704 and the sample table 1701, and thus can be preventedfrom being affected by charging as described above.

Sixth Embodiment

In this embodiment, a case where an ionic liquid introduction mechanismis provided above the sample table 1701 shown in the fifth embodimentwill be described. In the same manner as the fifth embodiment, on thesurface of the sample table 1701, a hole 1703, which has a diameter ofabout 1 to 5 mm and a depth of about 1 to 5 mm, is present, and an ionicliquid 1704 is held therein in advance. A probe 209 is moved and broughtinto contact with the ionic liquid 1704 held in the hole 1703 to adherea small amount of the ionic liquid 1801 to the tip of the probe.Thereafter, the probe 209 is moved, and the ionic liquid 1801 is adheredto a target position of the sample. By the above-described method, theliquid tank 201 in the ionic liquid introduction mechanism in the firstembodiment is no longer needed, and the ionic liquid can be guided tothe sample without adjusting the flow rate of the ionic liquid or thelike.

Seventh Embodiment

When an insulating sample is observed using an electron microscope, inorder to prevent the sample from being charged, after the sample issubjected to a conductivity imparting treatment such as metal coating,observation is made. However, metal particles are observed at a highmagnification, and therefore, in the case where faithful observation ofthe sample structure is desired to be made, such a treatment is notsuitable. When observation is made without performing metal coating,some effort is needed in some cases, for example, a condition whereelectric charges are easily discharged is provided by applying aconductive paste to the vicinity of the observation position in additionto the suppression of charging by adjusting the energy of electron beam,the amount of current, or the like. For example, in the case of apattern on a glass substrate or the like, when the pattern present atthe observation position continues to a distance on the millimeterorder, a conductive paste is applied to the end of the pattern to makeground connection, whereby charging can be suppressed. However, in thecase of a pattern in which the observation position is isolated, it isdifficult to make local ground connection using a conductive paste.Therefore, by using a wiring method described in the first embodiment,the ionic liquid is guided to the vicinity of the observation positionfrom a grounded position, for example, the ionic liquid is guided suchthat the ionic liquid surrounds the observation position, wherebyelectric charges are easily discharged to suppress charging, and thus,observation can be made.

Eighth Embodiment

As an observation method using an electron microscope, there is a methodof measuring an absorbed electron current of a sample. Further, as theapplication of the method, for example, the measurement of an electronbeam-induced current in a PN junction in a solar cell and the like canbe performed. However, the miniaturization and complication of recentelectronic devices have been advanced, and therefore, microwiring isneeded in many cases, and there are cases where wiring is difficult whenusing a solder or a conductive paste.

By using the wiring method as described above, local wiring can beperformed, and an absorbed electron current can be measured, andtherefore, the above-described problem can be solved.

Further, as described in the first embodiment, the ionic liquidintroduction mechanism has a mechanism to generate a potentialdifference between the tip of the probe 209 and the sample tableconnected to the ground, or to measure an electric current. Therefore,it is possible to perform the measurement of an electron beam-inducedcurrent as described above and the like by bringing the tip of the probe209 into contact with an electrode portion or a place wired from theelectrode portion. Further, by disposing a plurality of ionic liquidintroduction mechanisms, voltage-current characteristics between therespective probes can be measured and more complicated electricalcharacteristic measurement such as a two-terminal method or afour-terminal method can be performed. By the combination use with thewiring using the ionic liquid, flexible measurement according to thesituation can be performed.

Ninth Embodiment

As an observation method using an electron microscope, there is a needthat observation is desired to be made while applying a voltage, forexample, observation is made in a state where a voltage contrast isgenerated in a laminate structure by applying a voltage betweenelectrodes for the purpose of evaluating characteristics or analyzingfailures of a ceramic capacitor or the like. However, in the case ofperforming local evaluation, microwiring is needed, but there are caseswhere such wiring is difficult when using a solder or a conductivepaste. By using the wiring method as described above, local wiring canbe performed, and therefore, a voltage can be applied locally, as aresult, the above-described problem can be solved.

Further, it is also possible to use the absorbed electron currentmeasurement described in the eighth embodiment and the voltageapplication in combination. Further, when a plurality of ionic liquidintroduction mechanisms are disposed, a voltage can be applied not onlybetween the sample table and the probe, but also between the respectiveprobes.

Tenth Embodiment

With respect to an electron microscope, for example, there is a needthat observation is desired to be made while heating or cooling a samplefor the purpose of evaluating thermal characteristics of a metal, acrystalline material, or the like. An ionic liquid generally hasfavorable thermal conductivity and is said to be applicable not only asan electrically conductive medium but also as a thermally conductivemedium. Further, an ionic liquid stably takes a liquid state in a widetemperature range (from about −50° C. to 300° C.), and therefore can beheated to about 300° C. and cooled to about −50° C. In the case whereheating or cooling is performed using a conventional device, the wholesample is heated or cooled. However, for example, in the case where asample is surrounded by a thermally weak material and only a thermallystrong portion of the sample is desired to be heated, local heating isneeded. In the charged particle device of the present invention, theionic liquid can be used not only as an electrically conductive wiringline, but also as a thermally conductive wiring line, and therefore,local heating or cooling can be performed, as a result, theabove-described problem can be solved.

Eleventh Embodiment

FIG. 14 is a view showing one example of a GUI (Graphical UserInterface) screen for setting conditions for wiring using an ionicliquid. FIG. 19 is a view showing one example of a wiring systemprovided with an input device 1910 having a display device whichdisplays the GUI screen illustrated in FIG. 14, and a control device1903 which generates a signal for controlling a scanning electronmicroscope main body 1901 based on the wiring conditions set in theinput device 1910. Between the scanning electron microscope main body1901 and the control device 1903, an A/D converter 1902 for performinganalog/digital conversion of signals is connected. Further, a pointingdevice 1911 capable of setting an arbitrary position on the GUI screenis connected to the input device 1910.

On the GUI screen illustrated in FIG. 14, a display region 1401 in whichan SEM image is displayed and a processing condition input window 1407are provided.

The processing condition input window 1407 is provided for inputtingdevice parameters required for wiring, for example, the supply amount ofthe ionic liquid (Amount of Ionic Liquid), the wiring start point(Starting Point), the wiring end point (End Point), the size of the beamirradiation region (FOV (Field Of View) Size), the electron beam current(Beam Current), and the electron beam acceleration voltage (AccelerationVoltage). Further, along with the input to the processing conditioninput window 1407 or in place of the input to the processing conditioninput window 1407, the processing conditions can be input to the displayregion 1401.

In the SEM image illustrated in FIG. 14, two wiring lines 1403 and 1404are displayed, and this embodiment will be described by taking a processof connection between these two wiring lines as an example. First, thedrop position of the ionic liquid and the amount of the ionic liquid areexecuted based on the input of “Amount of Ionic Liquid” and “StartingPoint”. Incidentally, as for the amount of the ionic liquid, if there isa specified amount stored in advance, the ionic liquid may be droppedbased on the specified amount, and as for the drop position, theposition may be set using a pointer 1402. Based on the setting in such amanner, an ionic liquid discharge control section 1906 included in thecontrol device 1903 illustrated in FIG. 19 generates a signal forcontrolling the positions of the probe 209 and the sample stage 111 sothat the ionic liquid 1405 can be discharged at the specified position.Further, the ionic liquid introduction mechanism 113 is controlled sothat the specified amount of the ionic liquid can be discharged. In thecase where the drop position is set using the pointer 1402, a positiondetection section 1907 recognizes the specified position in the displayregion 1401, and a coordinate conversion section 1908 converts thespecified position to a stage coordinate or a control signal for theionic liquid discharge control mechanism 1906 and generates a controlsignal.

In addition to the input described above, by inputting “End Point”, theprocessing start point and the processing end point can be determined,and therefore, an optical condition setting section 1905 may set amoving track 1408 of the irradiation position such that both points areconnected to each other, or may set an arbitrary track using the pointer1402. Based on the above-described setting, the optical conditionsetting section 1905 generates a deflection signal for a deflector (notshown) for moving the beam irradiation position from the processingstart point to the processing end point as time passes, or a controlsignal for the sample stage 111. By providing such an irradiation regionmoving unit, the wiring can be automatically performed. In a memory1909, the generation conditions for control signals based on the inputconditions are stored in advance, and based on the generationconditions, a control signal is generated. Incidentally, the thicknessof the wiring line is determined according to the size of the beamirradiation region 1406, and therefore can be determined by the input of“FOV size”. The optical condition setting section 1905 generates ascanning signal for a scanning deflector (not shown) by setting the “FOVsize”.

Incidentally, if the processing start point, the processing end point,and the “FOV size” are determined, the size of the region to which theionic liquid is to be applied can be determined. Therefore, a table forstoring the size of the region and the amount of the ionic liquid inassociation with each other, or a relational formula thereof isregistered in the memory 1909 in advance, and the discharge amount ofthe ionic liquid may be automatically determined by setting theprocessing start point, the processing end point, and the “FOV size”.Further, if a large amount of the ionic liquid is discharged at oneposition, in the case of a sample in which a distance between adjacentpatterns is small, the adjacent patterns may be electrically connectedto each other. Accordingly, as illustrated in FIG. 20, it is desirablethat the size of an ionic liquid discharge region 2001 can be setarbitrarily. In this case, a table showing the relationship between thesize of the discharge region and the discharge amount or a relationalformula thereof is stored in the memory 1909 in advance, and based onthe table or the relational formula, the discharge amount may beautomatically determined.

Further, in the case where a discharge amount (D1) determined accordingto the processing start position, the processing end position, and the“FOV size” and a discharge amount (D2) determined according to the sizeof the ionic liquid discharge region 2001 satisfy the followingrelationship: D1>D2, the ionic liquid required for wiring isinsufficient, and therefore, for example, as illustrated in FIG. 20, anew ionic liquid discharge region 2002 may be provided to ensure thenecessary amount. In the case where the ionic liquid discharge region2001 is used as the processing start point and the processing proceeds,the processing passes through the ionic liquid discharge region 2002before the processing reaches the processing end point, and therefore,it becomes possible to continue the processing by using the ionic liquiddischarge region 2002 as a new processing start point (ionic liquidreplenishment point).

On the GUI screen illustrated in FIG. 14, after the processingconditions as described above are set, by pressing a start button(Start), the processing can be started. Further, if the moving speed ofthe irradiation position is too fast, the wiring line may bedisconnected, and therefore, a configuration in which the moving speedof the beam irradiation position can be controlled may be adopted.Further, the control may be performed such that scanning of a sampleregion displayed in the display region 1401 and scanning of the beamirradiation region 1406 (narrow range scanning) are continuouslyswitched to each other so that the process of the wiring can beconfirmed by visual observation. According to such control, it becomespossible to confirm the process of the wiring by an animated image.Further, as illustrated in FIG. 14, by enabling the set region of thebeam irradiation region 1406 to be visually observed, it becomespossible to visually compare the set processing region and the actualprocessing state.

REFERENCE SIGNS LIST

-   101: vacuum chamber-   102, 204: vacuum pumping system-   103: sample exchange mechanism-   104: charged particle beam source-   105, 1705: charged particle beam-   106, 1301, 1702: sample-   107: secondary signal-   108: secondary signal detection system-   109: control system-   110, 1302, 1701: sample table-   111: sample stage-   112: image display device-   113: ionic liquid introduction mechanism-   201: liquid tank-   202, 303, 702, 1704: ionic liquid-   203: inlet-   205: shutter-   206: probe rod-   207: rough movement mechanism-   208: fine movement mechanism-   209: probe-   301: probe fixing section-   302, 1703: hole-   401, 501, 704: ionic liquid droplet-   402, 502: Si substrate-   403: region to be irradiated with electron beam-   404, 503: region irradiated with electron beam-   701: target position A-   703: target position B-   1001, 1101, 1201: irradiation region A-   1002, 1102, 1202: irradiation region B-   1003, 1103, 1203: irradiation region C-   1302: sample table-   1303: sample exchange rod-   1304: sample exchange chamber-   1305, 1505: sample rotating rod-   1306: sample rotating rod control section-   1307: liquid bath-   1308: attachment-   1309: gate valve-   1501: sample rotating rod tip-   1502: sample table bottom-   1503, 1504: screw groove-   1801: ionic liquid

The invention claimed is:
 1. A wiring method, comprising: placing anionic liquid on a wiring track of a sample to be subjected to wiring,prior to irradiation of the sample using a charged particle beam; andirradiating the sample having the ionic liquid thereon with the chargedparticle beam to perform the wiring on the sample, the irradiating ofthe sample including forming a wiring line by attraction of the ionicliquid to a charged portion of the sample, and wherein an irradiationposition of the charged particle beam is moved along the wiring track.2. The wiring method according to claim 1, wherein the ionic liquid isdropped on the sample, and the ionic liquid dropped on the sample isirradiated with the charged particle beam.
 3. A wiring method,comprising: placing an ionic liquid at a first position on a sampletable to be subject to wiring and a sample at a second position on thesample table, the ionic liquid and the sample being apart from eachother; irradiating the ionic liquid with a charged particle beam toperform wiring on the sample table; and forming a wiring line by movingan irradiation position of the charged particle beam moved from thefirst position where the ionic liquid is placed to the second positionwhere the sample is placed.
 4. The method according to claim 1, whereinthe ionic liquid is at a first position on the sample, and theirradiation position of the charged particle beam is moved along thewiring track from the ionic liquid at the first position to a targetposition on the sample, the first position and the target position beingapart from each other.
 5. The method according to claim 1, wherein theirradiating of the sample includes irradiating the wiring track havingthe ionic liquid thereon.
 6. The method according to claim 1, whereinthe irradiation position is sequentially moved along the wiring track astime passes.
 7. The method according to claim 1, wherein the irradiationposition is moved so that one irradiation position and a subsequentlyirradiated irradiation position overlap with each other.
 8. The methodaccording to claim 1, wherein the irradiation position of the chargedparticle beam is moved along the wiring track using a deflector.
 9. Themethod according to claim 3, wherein the forming of the wiring line iscaused by attraction of the ionic liquid to a charged portion of thesample.
 10. The method according to claim 3, wherein the ionic liquid atthe first position is a first ionic liquid supply, and the methodfurther comprises: placing a second ionic liquid supply at the secondposition where the sample is placed, the second ionic liquid supplybeing smaller than the first ionic liquid supply.
 11. The methodaccording to claim 3, wherein the forming of the wiring line includesmoving the sample table, using a sample stage coupled to the sampletable, so that the irradiation position of the charged particle beam ismoved along a wiring track of the sample table.
 12. The method accordingto claim 3, wherein the ionic liquid is placed in an ionic liquidholding member of the sample table.
 13. The method according to claim 3,wherein the irradiation position is sequentially moved along a wiringtrack of the sample table as time passes.
 14. The method according toclaim 3, wherein the irradiation position is moved so that oneirradiation position and a subsequently irradiated irradiation positionoverlap with each other.